This project focuses on leiomyomata (fibroids) and endometriosis and examines factors related to their pathogenesis, diagnosis and/or potential treatment. Ongoing work seeks to evaluate the utility of the progesterone response modulator CDB2914 as a treatment of fibroids. A randomized, double-blind, placebo-controlled phase II study evaluates whether surgical excision of endometriosis followed by daily administration of raloxifene for six months reduces pain for a longer time than surgery alone. We characterized the spatial and temporal localization of estrogen receptor (ER) alpha and breast cancer nuclear receptor auxiliary factor (Brx) in eutopic endometrium of 35 healthy women and 29 women with endometriosis. Samples were obtained during laparoscopic laser excision surgery. Expression of ERalpha and ERbeta was highest in the proliferative phase and was similar in both groups. Brx expression differed between healthy volunteers and those with endometriosis. During the proliferative phase, immunostaining intensity of Brx was greater in both the glandular and stromal compartments of biopsies from patients with endometriosis compared to healthy volunteers; nuclear stromal Brx staining was more common in patients with endometriosis. The spatiotemporal expression of Brx was altered in eutopic endometrium of women with endometriosis. These findings suggest a fundamental alteration in the endometrium of women who have endometriosis. The role of Brx in ectopic implantation of endometrium deserves further study.